Tractor rollover is one of the most serious safety problems in the process of agricultural mechanization, which has not yet been essentially solved by current technical means. In previous study, an external flywheel-based stability control system was designed to realize attitude stabilization of an unstable tractor, basing on the principle that an accelerating flywheel can generate a reverse torque. To avoid energy waste during the unloading process of the decelerating flywheel after active attitude control, an energy harvesting circuit was proposed and tested on the 1∶16 scaled model test platform. The testing results showed that the energy harvesting system effectively worked when the roll angle of the tractor was reduced to 10°. Correspondingly, the peak value of the harvesting voltage rised to 0.97V (H-B trajectory) when the model tractor traveled at 0.2m/s on the G-class and H-class roads. Similarly, the voltage responded to decrease to zero as the flywheel decelerated after the active attitude control of the tractor was accomplished. In all the tests, the system proved the ability of harvesting electric energy, which improved the energy utilization efficiency of the tractor attitude control system. The approach and the results of this work may help theoretical fundamentals for optimization of the energy efficiency in a flywheel-based tractor active stability control system.